Controlling device



Jan. 10, 1950 c. s. BAKER 2,494,279

- CONTROLLING DEVICE Filed Oct. 12, 1944 i I INV N'TOR 30 Charles Balfiea. Eg-J. BY

HIS ATTORNEY.

Patented Jan. 10, 1950 CONTROLLING DEVICE Charles S. Baker, Corning, N. Y., assignor to Ingersoll-Rand Company, New York, N. Y., a corporation of New Jersey Application October 12, 1944, Serial No. 558,429

This invention relates to an air compressor One object of the invention is to provide a compressor system which eliminates the necessity for an air receiver.

Another object of the invention is to provide a system of this type which unloads the compressor and slows its driving motor when the demand for air ceases.

Other objects and advantages of the system will be in part obvious and in part pointed out hereinafter.

The drawing illustrates a preferred embodiment of the invention and includes Fig. 1, an elevation view 01 a, compressor, its driving motor and regulators constructed in accordance with the practice of the invention, together with a pneumatic tool adapted to be associated therewith,

Fig. 2, a detailed view partly in longitudinal section of the speed regulator for the motor and the connection to the throttle valve thereof, and

Fig. 3, a vertical section through the compressor unloader.

As indicated in Fig. l, the compressor system comprises a compressor which is adapted to be driven by a motor H in this case a gasoline engine, a speed regulator i2 for the engine II, and an unloader It for the compressor Ill associated with a discharge conduit 1 4 which in this instance is shown adapted to conduct compressed air to a pneumatic drill 15. As will be noted, the compressor it] is not provided with an air receiver ii .and the discharge line [4 is directly connected with the tool to be operated. interposed in the discharge conduit I4 is the unloader l3 which in this instance is provided with a casing having a base H5 and a cover portion l6 suitably bolted piston is kept at an elevated position as shown in Fig. 3.

Also formed in the base H5 is the cylinder within which is adapted to reciprocate a spool valve 2! for the control of the pressure relief 2 Claims. (Cl. 230-11) port 22 formed in the wall of the cylinder 20. A

' 2 stem 23 connects piston 88 with the spool valve 2| 50 that the two move together as a unit.

The cover I5 is provided with a cavity 123 forming a convenient passage for air flowing from the groove I9 to the conduit I4. Cavity i23 also permits the upper face of the piston I 3 to be exposed to air pressure from above. Normally the piston I8 is biased toward the downward position (Fig. 3), by means of a coil spring 24 contained within cylindrical pocket 25 formed integrally with the cover It and which acts as an upper stop for the piston i8. The petcock 26 is provided in the cover IE to communicate with the cavity 23.

The gasoline engine H is provided with a conventional form of carburetor '2! at its intake 28 and its speed is controlled by a suitable butterfly valve 29. For regulating the speed of the engine ii there is provided the regulator :2 which is responsive to the pressure in the'discharge conduit I4. In this instance, the regulator [2 comprises a diaphragm 30, mounted within a housing consisting of a base portion 3| and a cover 32 suitably bolted together With the diaphragm 30 'between them. The space between the cover 32 and the diaphragm 30 indicated at 33 is a pressure chamber adapted to receive pressure fluid from the discharge conduit M by way of a suitable pipe 34 attached at a threaded aperture 35 in the base 3| which communicates by way of a hole 36 through the diaphragm 3B and a port 3'! in the cover 32 with the pressure chamber 33. Diaphragm 3!] is adapted to transmit force to a plunger 38 having a head 39 and a nut 40 for gripping the diaphragm 30, suitable washers 4| and 42 being provided under the head 39 and the nut 43 respectively. Plunger 38 extends through a threaded aperture 43 having a correspondingly threaded bushing 44 which is adapted to be screwed into and out of the base 3! and which acts as an adjustable stop for the rod 38 in cooperation with the nut 49. Bushing 64 may be locked in place :by means Of a nut 45. Pressure exerted against the diaphragm 35 by fluid within the chamber 33 is opposed by a spring 46 contained within the base 3! and bearing against the washer 42. The pressure of the spring 4-6 is merely suihcient to overcome the idling pressure of the compressor i0 and to operate the throttle valve 29 as will be described.

Force exerted on the rod 38 is adapted to operate the throttle valve through a system of links and levers including lever 47 suitably pivoted at the stud 48, a link 49, lever 50 and link 5! attached to the arm 52 of the throttle valve 28. Levers 41 and 50 are suitably pivoted at the stud 48 and pivot 53 respectively mounted on the engine base. Rod 38 is attached at the pivot 54 intermediate the ends of lever 41. At the swinging end of the lever 4! is attached a pivoted member 55 slidingly engaging the rod 49 the effective length of which is adjustable by means of a nut 56 provided on the rod 49 and corresponding locking nuts 5'! forming an abutment for a spring 58 about the rod 49 and bearing against the member55. At the end of the link 49 the forked end 158 thereof is pivotally attached as at 55 to the lever 53 intermediate its ends. The swinging end of .the lever 50 is pivotally attached as at fill to the link 5!. The opposite end of linkl5! isprcvided with an adjusting nut 6i which adjusts the effective length of the link.

The motion of the throttlevalve 29 is a function of the motion of the rod 38 and accordingly the degree of movement is governed by the adjustment of the sleeve 44 which is adapted to contact themutiMl and a stopxor boss fiZ which is adapted to contact the head "39 of :the :rod 38 when the pressure within the'cham'ber 33 is reduced.

.Asfindicated inFig. -1 the compressor system is adapted to operate a pneumatic hammer drill indicated at l5 which may be provided with a suitable tthrottle valve- 63. When the system is in operation, that'isito say, when the engine is running and the drill I5 is drilling with the throttlevalveilis iopemairIflcws through the conduit i'fiiand intits passage through the unloader -l3provides pressureagainstthe relatively large area of the piston. l 8 .on its lower side to hold that piston iniits extreme .upwardposition. Air thus fiowsthrough "the groove is and thence to the tool 15 The size=ofthe groove iii is'preferably regulated so that an :appreciablepressure drop exists :onithe upper and'lower sides of the piston 18. .If it beassumed that a normal pressure of ,80 pounds perisquare inchis provided at the compressor 19, a suitable pressure drop of say, five pounds would :be adequate'to'hold the piston in its:upward: ositionegainst'the pressure of spring .24. "No unbalance isprovided by the associated relief valve 12! since that valve is provided with an'equalizing port fificonnecting both of the ends of the cylinder .25. At the same time, pressure fiuid'from the discharge conduit I4 is admitted by way of the pipe 34'to the'pressure chamber 33 depressing the diaphragmso. and through the associated'systemof links and levers the throttle .valve 29 is forced to its open position.

.Upon closure of the throttle valve 53 the pressure on opposite faces of the'piston i8 imme- -'.diately balance, permitting the spring to depress the piston 'and'the valve 25 to uncover 'thevent '22 whereupon the pressure in the conduit :ia'4 very soon drops to: a relatively low value. Correspondingly, the pressure within the chamber 33 cfrregulator l2 drops permitting the spring 45 to force .the' rod 38 toits extreme position toward the left, thereby closing the throttle 29 to its idling position. Itis preferable that while idling the compressor ill should produce =a relatively small pressure, as for instance, about l5 pounds within piston 18 to close the relief valve.

the conduit i4. Obviously, the vent 22 cannot be sufliciently large to drop the pressure within the conduit to zero, because upon reopening of the throttle valve 63 there would be relatively no flow of air to the tool. It will, therefore, be seen that the minimum pressure within the conduit I4 will be that which will produce a pressure differential on the piston l8 sufficient toforce the piston l8 to an upward position when the throttle valve 63 is open. When a relatively small tool is connected to the conduit 14 the flow of air through the conduit may not be sufficient normally to cause a pressure drop which would operate the For this purpose the petcock zfi is provided which, when open provides anadditional flow of air to cause such a pressure drop. Since in such an instance the compressor i5 is more than adequate in capacity to operate the tool the loss of air through the petcock leis of no great consequence. 'Also,'when idling'the slightpressure drop existing on'the piston IS-due to the opening of the petcock 26 will not effect the operation of the piston. Its function is to help the action of the piston by increasing the pressure differential.

Thus by the above construction are accomplished among others, the objects hereinbefore referred to.

I claim:

1. In a controlling device, the combination with a: compressor, amotorfor driving the compressor, a-discharge conduit for said compressor, a speed regulator for the motor acting responsively to the pressure in said discharge conduit, a relief valve in said discharge conduit, of a guiding cylinder forming part of said conduit,-apiston in said cylinderacting responsivelytothe flow of .fluid in said 'ICOndUlttO close said relief valve, a .stem connectingsaidpiston with said-relief valve, and a spring biasing said relief valve tolits open posi tion.

2. In a controlling device, the combination with a fluidcompressor, adischarge conduit for the compressor having an exhaust port, a relief valve in the conduit to control the exhaustportof a guiding cylinder forming part of the conduit, a piston in said cylinder responsive to the how of fluid inthe conduit to'operatesaid relief valve, astem connecting said piston with said relief valve, and a spring biasing said relief valveto its open position.

CHARLES S. BAKER.

REFERENCES CIT-ED The following references are of record in the file of this patent:

U NITED .STATES PATENTS Number Name Date 1,895,480 -McCune Jan. 31, 1933 1,942,433 Lindsay Jan. 9, 1934 2,378,802 Slater June'19,'194 5 

